Short answers, pulled from the story.
Monks carrying the relics of St Cuthbert settled at a place called Dunholm in 995 CE. They chose this site because the River Wear formed a horseshoe-like defensive curve around it.
County Durham existed as a private shire where the bishop appointed his own sheriff and governed with virtually autonomous power from 1075 until 1536. The Jurisdiction in Liberties Act 1535 deprived the bishop of power to pardon offences or appoint judicial officers.
The number of people employed in coal mining rose to a peak of 157,837 in 1921. Most collieries closed during the last quarter of the twentieth century leaving no deep-coal mines in the county today.
The historic boundaries stretched from rivers Tyne to Tees until the Local Government Act 1972. The ceremonial county borders Northumberland and Tyne and Wear to the north and Cumbria to the west.
Spennymoor Settlement opened as Pitman's Academy in 1930 funded by Pilgrim Trust. It aimed to encourage neighbourliness during Great Depression when unemployment was widespread.